Plastic nozzle plate for missile motors



Aug. 14, 1962 s. H. HERZOG PLASTIC NOZZLE PLATE FOR MISSILE MOTORS FiledOct. 24, 1958 INVENTOR. STEPHEN H. HERZOG ilnited rates Patent U3,048,970 PLASTIC NOZZLE PLATE FOR MISSILE MOTORS Stephen H. Herzog,China Lake, Califi, assignor to the United States of America asrepresented by the Secretary of the Navy Filed Oct. 24, 1958, Ser. No.769,517 3 Claims. (Cl. 6035.6) (Granted under Title 35, US. Code (1952),see. 266) The invention described herein may be manufactured and used byor for the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to rocket motors; more specifically, it relatesto improvements in discharge nozzles.

Steel discharge nozzles for rockets have been used successfully in thepast. The use of higher energy propellants, however, brought about theuse of erosion-resistant inserts in the constricted part of the nozzlewhere the erosion is greatest. Some of the present propellants are soenergetic that the steel around the insert erodes away during operationof the motor, allowing the insert to be expelled from its seat.

Further, the steel nozzles used in the past have been fairly heavy ofnecessity, due to the rather substantial construction required.

It is therefore an object of this invention to provide a nozzle havingan erosive-resistant insert which will not be expelled during operationof the motor.

A further object is to provide a nozzle which is considerably lighterthan existing steel ones, while having a nozzle insert which will not beexpelled during operation of the motor.

With these and other objects in view, as will hereinafter more fullyappear, and which will be more particularly pointed out in the appendedclaims, reference is now made to the following description taken inconnection with the accompanying drawings in which:

FIG. 1 shows a plan view of the nozzle plate assembly;

FIG. 2 shows an elevational crom-sectional view taken along line 2-2. ofFIG. 1, and

FIG. 3 shows a cross-sectional plan view taken along line 33 of FIG. 2.

Referring now to the figures, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown a nozzle plate 11 having a plurality of exit ports asshown, each port having a beveled surface 12. The plate 11 has a raisedcenter portion 13 on the side opposite to the side shown in FIG. 1 whichis provided with a threaded hole extending through the raised portionand plate; plate 11 is further provided with a circumferential skirtportion 14 made integral therewith. A disk 15 is positioned inside theskirt portion in contact therewith and is provided with a plurality ofexit ports corresponding to and in alignment with the ports in plate 11,the ports of disk 15 having beveled surfaces 16 so as to form a smoothcontinuous surface with the beveled surfaces 12 of plate 11. Disk 15 isprovided with a well, as shown, to receive the raised portion 13 ofplate 11 and to remain in contact therewith. A threaded hole extendsfrom the bottom of said Well to the other side of disk 15.

Tubular inserts 17 are provided in the ports of disk 15, said insertshaving beveled surfaces 18 which form a smooth continuous surface withthe beveled surfaces 12 and 16 of plate 11 and disk 15, respectively.Inserts 17 are also provided with inner beveled surfaces at the endopposite to the end having beveled surfaces 18. The parts of disk 15 arefurther provided with beveled surfaces 19 3,943,973 Patented Aug. 14,1962 at the end opposite to the end having beveled surfaces 16.

Rupture diaphragms 21 are provided in the hollow inserts to seal theopenings until the motor is ignited, whereupon they are ruptured.

Plate 11, its skirt portion 14, and raised center portion 13 areconventional and made of steel.

The inserts 17 are highly resistant to erosion and are made of graphite,a refractory metal, or certain metal oxides, all well known for theirresistance to erosion.

The disk 15 is made of a thermosetting resin, preferably aphenolformaldehyde resin which incorporates up to 70% of a filler. Thefiller is preferably chopped glass or asbestos though other materialscould be used. The preferred resin is one having a low degree ofpolymerization. The filler may be glass, asbestos fibers or metalparticles and filaments, though asbestos or glass fibers are preferred.

In practice, the steel plate 11 is first machined; the plastic portionis made separately and press fitted into position.

The plastic disk 15 is made by positioning the erosionresistant insertsin a suitable mold, pouring in the resin to which the filler has beenadded and blended, and heat treating the mold to cure the resin. Therupture diaphragm is thus molded in place in this operation.Alternatively, the steel plate 11 and integral skirt 14 may be used aspart of the mold and the disk 15, the inserts 17 and blowout diaphragms21 molded in place.

In assembling a rocket motor incorporating the nozzle assembly of thisinvention, the combustion chamber is first loaded with propellant andignition means, and the nozzle plate assembly is screwed into positionat the end of the combustion chamber.

A number of the instant nozzle plate assemblies have been tested underthe same conditions that caused conventional steel nozzle plates toexpel their erosion-resistant inserts and no such expulsion wasobserved.

What is claimed is:

1. An erosion resistant nozzle plate assembly comprising a metal platehaving an annular skirt portion on one side thereof and at least onedischarge port therein, the walls of each discharge port increasinggradually in diameter from the side of said plate having the annularskirt portion to the opposite side of said plate, a disk ofheatresistant plastic material having a diameter equal to the innerdiameter of said plate skirt portion fitting within said skirt portionand in contact with said plate, said disk having a number of dischargeports therein equal to said at least one port in said plate and inalignment therewith, the walls of each discharge port in said diskincreasing gradually in diameter from a smallest diameter at a pointintermediate the two faces of said disk to the outer face thereof, thelargest diameter of each discharge port in said disk at the face thereofwhich contacts said plate being equal in diameter to the smallestdiameter of said at least one discharge port in said plate, a tubularnozzle insert of erosion-resistant material imbedded in said disk portWalls at said intermediate point being completely separated from saidplate by the material of said disk and having walls coinciding with saiddisk port walls, whereby a converging-diverging nozzle having smoothsurfaces is formed by the beveled surfaces of the aforementioned partsand a heat barrier is formed between the nozzle surfaces and said metalskirt.

2. The device of claim 1 wherein the disk portion is made of aphenol-formaldehyde resin incorporating from about zero to about 70% ofa filler selected from the class consisting of asbestos and glass andsaid insert is made of graphite.

zap same 3. A nozzle plate assembly for rocket motors comprising a steelplate having a circumferential steel skirt and a plurality of exit portstherein each of which has a beveled surface, a heat-resistant rosin diskpositioned within said skirt, said disk having a plurality of exitopenings in alignment with the exit ports of the steel plate and eachopening being provided with a beveled surface, and a tubularerosion-resistant insert embedded Within the Walls of each of the exitopenings of said disk, each insert being insulated from said steel plateby the resin of said disk and having a beveled surface, and the beveledsurface of each exit opening of said disk merging with the beveledsurfaces of its associated insert and exit port to provide a smoothcontinuous surface.

References Cited in the file of this patent UNITED STATES PATENTS2,755,620 Gillot July 24, 1956 2,835,107 Ward May 20, 1958 2,849,860Lowe Sept. 2, 1958 2,939,275 Loedding June 7, 1960 2,958,184 SandersNov. 1, 1960 2,968,919 Hughes et a1 Jan. 24, 1961 2,987,874 NicholsonJune 13, 196 1 FOREIGN PATENTS 1,135,050 France Apr. 23, 1957 757,890Great Britain Sept. 26, 1956 l

